This project attempts to explore the developmental biology of the immune response beginning in utero and continuing in neonatal life, childhood, and aging. It also proposes to determine by immunologic means whether magnitudes of immune response to selected antigens, in terms of both cellular and humoral immunity, are linked to histocompatibility antigens, and whether certain immunological diseases, some known to be genetically determined and some of unknown causes, are linked to HLA antigens. We also propose to use immunologic means to study the genetic mechanisms operative in genetic diseases of childhood which at the present time are poorly understood, and to attempt to prove that other diseases of unknown causes are genetic in origin. We hope to utilize immunologic means for establishing diagnostic tests for certain diseases in which diagnosis is often difficult until the disease is far advanced. We also hope to show that aging is due to immunologic mechanisms and perhaps that these mechanisms are genetically determined, thus explaining longevity as a feature common to certain families.